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UNITED STATES PATENT OFFICE.

CHARLES W. BROWN, OF MONTREAL, QUEBEC, CANADA, ASSIGNOR TO THE BELLTELEPHONE COMPANY OF CANADA, OF SAME PLACE.

TELEPl-IONE- SYSTEM.

SPECFICATION forming part of Letters Patent No. 393,612, dated November27, 1888.

Application led March 31, 1888. Serial No. 269.211. (No model.) Patentedin Canada Api-i116, 1888, No. 28,932.

To @ZZ whom it may concern:

Be it known that I, CHARLES WARREN BROWN, of the city of Montreal, inthe district of Montreal and Province of Quebec, Canada,

have invented certain new and useful Improvements in Telephone Systems,(for which Letters Patent of Canada, No. 28,932,were granted to me onthe 16th of April, 1888;) and I. do

hereby declare that the following is a full, 1o clear, and exactdescription of the same.

The system to which my invention applies is that which has been adoptedforlarge buildings to secure telephonie communication between thenumerous departments therein.

Such a system is shown anddescribed in Patent No. 356,427, granted to C.E. Scribner, and which he calls a Factory Telephone EX- change, butwhich can also be styled a local system. Such systems consist, essen- 20tially,of a separate instrument for each department, embraeingakey-board and plug,a callbell, transmitter, battery, and telephone, andthe necessary connections. In addition to its adaptability to largebuildings, such a system can also be used for local com municaton,suchas between a main building or department and outbuildings in immediatevicinity, and also for village telephonie communication, if desired. Inall such cases, however, for outside 3o work or communication withanother system a separate and distinct general telephone is required,and of course to this all parties in the building or community must cometo hold communication with the exchange and outsiders.

The purpose of my invention is to do away with this-general telephonealtogether and give to each department or station in such local systemseparate connection with the eX- change, in addition to their presentpower of speaking to any other department, and obviously allow exchangeto call either of the departments. This object I attain by certainalterations in and additions to the mechanism for local communicationabove alluded to, which changes will now be brieliy described.

I have separate instruments for each department, each of which includes,first, a keyboard and plug, the sameas before, except 5o that anexchange `key and push-button are added; second, a call-bell, the sameas formerly, for signaling between the departments only; third, atransmitter differing from. ordinary construction in so far that itsbattery has a complete circuit separate from the sec- 5 5 ondary circuitof the induction-coil; fourth, a telephone the same as formerly; fifth,a system of insulated springs operated by the telephone-lever to cuttelephone iny and out and to open and close the separatetransmitter-battery circuit, also serving to keep closed theexchangecircuit, in which are arranged extension-bells to allow theexchange to call any particular department by special signal. Inaddition to these instruments I have a main or` calling battery commonto all of them, instead of an independent battery for each. Besides thisthe arrangement of the line connections and the foregoing mechanism issuch as will enable one station,as formerly,to call another withoutcalling other stations in the system, and also to allow any departmentto call the exchange without calling the other stations. Further, thearrangement renders possible a test as to whether the local circuit ofeach station is clear by each station without calling other stations,and provides means, in connection with the exchange-key, for calling theeX- change, and a push-button whereby the eX- change speaking-circuit isclosed. For full comprehension, however, of the invention reference mustbe had to the annexed drawings, in Which- Figure l is a diagram of asystem comprising three stations, two of which are shown incommunication,the telephones being removed fromv their hooks orswitch-levers, and the third in its normal position; Fig. 2,a sectionaldetail of thekey-board, the section being taken so as to show theparticular key for calling the exchange and the push-button for keepingthe talking-circuit from same closed; and Fig. 3 is a detail of a pairof insulated springs on the eX- change-line operated by thetelephone-lever to keep same always closed, so that the eXtension-bcllscan be rung at any time.

`Similar letters of reference indicate like parts.

As all the parts or mechanism of the system are well known to thoseskilled in the art to which this invention appertains, it is notconsidered necessary to illustrate them other- ICO wise than by diagram.lt must also be understood that while the outtit of only three stationsor departments is shown any number may be included in the system.

Referring to Fig. l, I showin diagram in the stations Nos. l, 2, and 3the several parts or elements of an outtt, all of which, except theextension-bell, will of course be mounted on a board of the usual kindand arranged upon the wall. The extension bell will by preference beplaced out ot' the way upon some convenient shelf.

A represents the key boards,eaeh composed ot' t'our keys, a/ It La a,ot' the kind shown in section in Fig. 2-vi7.., a metal base or stud witha central plug-hole and a projecting [lat metal spring to be depressed,so as to make contact with the united terminals b' b Il b of wires n,"ai w from one pole of the main or calling battery X, which is com mon toall the stations and situated in any convenient partofthe building.

a' a a are the calling-keys of each station in the system, and a is tocall the exchange. The connections between the keys of the severalstations are made by wires cc'fcias shown. An additional key,a", l'orclosing the exchange talking-circuit, is provided, and consists of a latmetal spring, a", projecting from the opposite side of the stud ot` keyrt* and provided with a button or more convenient means-such as a handcam-lever-acting on its free end t'or holding it depressed (whiletalking is going on) upon a terminal at end of a terminal wire, b5,ofthe secondaryeircuit ofthe transmittercoil, so as to leave one of thespeakers hands free in ease he should want to write down a message. Asthese several keys are normally out ot` contact with the severalterminals and the circuit naturally broken, and as it is of coursenecessary that the exchange-circuit shall always be closed in order toring the extensionbells at any time, I arrange a bridge, b", over thespring ot key a, and by means ot' this bridge and a screw set in sameand bearing upon the spring a permanently-closed exchange-circuit issecured, as the exchangeline e* is carried into the station No. lY andconnected, first, with the stud of exchangecalling key a, whence thecircuit continues, through spring a, screw, and bridge b,toacontinuation ofthe exchange-line. This continuation leads from bridgebof station No. l to exchange-calling key a* and bridgeb"of station No.2, and so on through a furthercontinuation of the line to the same partsin station No. 3, a closed circuit being maintained throughout all theseparts. From the bridge in the last, or No. il, station the exchangelineis carried back to No. l, where it is divided in two and terminates intwo springs, de, one on each side ot the switch-arm ot` thetelephone-hook ll, but never coming in contact with it. Similar springs,d c', forming the terminals of the divided end ofa continuation, c,ofthe exchangeline, on which the extension-bell E of station No. l isarranged, are furnished with knobs d'2 c2, of insulating material, whichcome in contact with the switcharm, but of course have no electricalconnection with it, and arc acted upon by it to canse the respectivepairs of springs Z d and c c to make electrical contact. These springsare t'or the purpose of maintaining an unbroken exchange-circuit at thispoint whether the telephone be on the hook or ott', and this is donewhen the telephone is on the hook bythe switch-arm, as shown in No. 3station, pressing spring e into contact with spring c, and when thetelephone is ot't`, as shown in stations Nos. 1 or 2, by the contact of(t and ft. rlhis duplicate arrangementot'springs is provided in eachstation, as shown, and it will be seen that the unbroken circuit passesthrough all the extension-bells E t0 ground.

Anystation (say No. 3) can call the exchange without calling otherstations by pressing key a", which closes t-he break bctnveen exchangeline and main calling-battery X, and the current travels 'um theexchangedines between the several stations and through the bridges b,springs a, and their studs in stations Nos. 2 and 1 to exchange.

F l Fiare the caltbells of each station, and l. N the bindingposts ofsame, one, l?, of which is connected by wire p topositive pole or earthline ot battery X, and the other by wire n tothetelephonehooks,which,whenthetelephone is hung ou either 0l' them,make electrical contact with either ol' the springs n' nf" a, a' formingthe terminal of calling-key wire c, 11F' the same of branch c' fromcalling-wire c, and n" the same of branch 0 from calling-wire c.

Suppose No. 3 desires to call No. l, whose instrument we will presume isin its normal condition, the same as No. 3. No. presscs key Land thecurrent travels along wire c to spring n', through telephone-hook, alongwire n, to call-bell F, and through same to earth by line p, this beingdone without calling No. 2 in any way; and, again, if No. 3 desires totest his callbell to see it his own circuit is clear, he will press thekey of his own station (marked 3) and make a battery-circuit from poleor terminal t", up line c, down its branch 0", and back to key 3 byspring or", telephone-hook, wire a, through call-bell F, and by Wire pto opposite pole ot` battery or earth-line. It will be seen that noother station is called during this operation.

All the parts of the instruments are normally in the position shown inNo. 3 station, the telephone hanging on the hook and its switch armkeeping the exchange circuit closed by operating upon springs e c', andthe call-bell circuit in the same state by switclr arm bearing againstspring n 1" l* l3 are the transmitters,of ordinary construction, savcthat I make its battery-circuit complete without becoming a part of thesecondary circuit of the induction-coil.

t t'' represent the terminals of this complete ICO battery-circuit inthe form of springs similar to those in the exchange-circuit andarranged on one side of the switch-arm, one, t', being always out ofcontact with the arm, but the other, t, insulated fomit by a knob, ofrubber or other material, being operated by it when the telephone isremoved to close the break between them and so work thc circuit.

S S2 S3 represent the telephones with their terminals connected,respectively, to earthlines and to one terminal, s, of the secondaryeoil of the transmitter, while a plug, z, is connected to the oppositetransmitter terminalwire, b5

After calling any particular station by depressingthe necessary key, theparty calling inserts plug z in the plug-hole in the stud of that key,and as the party called also inserts his plug in the key bearing thenumber of his own station telephonie communication is established, asshown, between stations Nos. l and 2, the telephone being of course offthe hooks. The speaking circuit between these two stations is fromground terminal of and through telephone S', along terminal s of andthrough secondary coil of transmitter, along terminal b, through plug ato key marked l, whence it follows Wire c to key l in station No. 2 andtakes a corresponding course from this point through transmitter andtelephone to ground.

l. The ombination, with a local telephone system in which each stationcan call andcommunicate directly with another independently of anyspecial station or centralizing point to which the line of each stationmust converge, of a line-connection or closed circuit from an outsideexchange entering each station, a signaling device (such as anextension-bell, E) in each station with which said line-connection isalways in closed circuit except when either of the stations is intalking circuit with ceutral station, so that central can call anysubscriber by special signal, a key in each station to enable it toconnect a calling-battery circuit Vwith said line-connection or closedcircuit, so

as to call such outside exchange, and meanssuch as a key-in each stationfor connecting its telephone-circuit with the said lineconnec tion orclosed circuit, all as herein set forth.

2. In the individual station of a local telephone system, thecombination of an individual local circuit-closing key or terminal ofsuch station, a terminal of one pole of a main battery-circuit, and acircuit confined to such station connecting such calling-key throughspringcontact and telephone-hook with one terminal ot' an electro-magnetfor operating callbell, the other terminal of the magnet leading to theother pole of said battery-circuit or to ground, all arranged andoperating in the individual station, as herein described.

The combination, in a telephone system of a central-exchange ofiice,of alocal system in which each station can call and communicate directlywith another independently of any special station or centralizing pointto which the line of each station must converge, and a line-connectionor closed circuit from the exchange entering each station in localsystem and composed of main line leading to iirst station in localsystem, extensionflines between each station connected at stations bydevices adapted to open and close circuit,and further extension-linesbetween each stat-ion and to ground carrying signaling devices, thepairs of springs d d and c e in each station of the local systemconnected with said further extensionlines', and means for securingcontact of each of said pairs, as and for the purpose described.

C. XV. BROVN.

itnesses:

Fans. HY. RnYNoLDs, WM. P. MoFEAfr.

